Variable electrical condenser



Oct. 20, 1925- 1,557,725 J. A. PROCTOF'E VARIABLE ELECTRICAL conmmsm Original Filed Feb. 1921 Mimi HT W 7 INVENTOR Ja hn JlProcDr A TTORNEY Patented o... 20, 1925.

UNITED STATES PATIENT 6mm.

IOU A. PBOC'NB, Of LEXINGTON, IASSACHUSBTTS, A BSI GNOB SPE- VARIABLE ELmTgICAL CONDENSER.

Original application fled February 1, 1911, Serial I9. 1,8. Divided and this application fled July 9,

1am. Serial Io. man.

To all whom it may concern:

Be it known that I,' JOHN A. Paocroa, a citizen of the United States of America,

and a resident of Lexington, State of Massachusetts, have invented certain new and useful Variable Electrical Condensers, the principles of which are set forth in the followlng specification and accom anylngdrawing, which disclose the form 0 the invention which I now consider to be the best of the various forms in which the principles of the invention ma be embodied. This ap lication 1s a division of my application rial No. 441,628, filed February 1,1921. I

This invention relates to variable electrical condensers for general use, especially for high potential uses, such as in radio transmitters, power factor lines and wherever high potential condensers are found necessary. The invention claimed in this divisional application relates more particularly to a variable condenser of the enclosed casing tvpe, preferably having a vacuum dielectric and provided with means for varying the condenser capacity by relative movement of the condenser conductors or armatures of opposite polarity. This variable 3 suitable for use at any desired voltage.

In condensers of the sheet or jar t now in use, the electrical losses where hig voltages are used are comparatively gre at resulting in loss of efliciency; and also in heating and ultimate disintegration of the condenser, especially if not properly made. This heating is partly due to losses in the dielectric apparently arising from dielec- -tric hysteresis or.frictionally-impeded movements of the atoms of the dielectric due to electric flux through the latter, and partly because of brush or corona discharges in the medium surrounding such condensers.

An object of the present invention is to.

4 provide a construction in which. preferably the losses are at a minimum. In part cular,

condenser can be constructed so as to be the invention comprises a variable condenser in which the principal dielectric preferably is a vacuum. Briefly described, the vari-' able condenser of this invention in its referred form comprises a suitable casing, bulb or tube in which is mounted a condenser made up of spaced metallic plates, th airbeing exhausted from the casing to form between the plates a vacuum dielectric in which there is no appreciable loss in use due to gas ionization or to dielectric hysteresis; .and means operable from the ex terior of the casing to cause relative move ment of the interior condenser. conductors and corresponding variation 9f the condenser capacity.

The drawing is a perspective view of the embodiment of the invention in a variable condenser.

This variable condenser comprises spaced fixed metal plates 25 mounted u on and electrically connected to metal 26. Fixed plates 25 are spaced from each other by any suitable means such as the metal sleeves-27. The rods 26 are in turn secured to metal end plates 28. fixed 'atspaced distances apart, and in such position as to alternate with the spaced plates 25, to a metal shaft 30 journaled in insulators 31 fixed in the end plates 28 to insulate the two sets of plates from each The upperportions of end plates 28 are cut away, forming spaces 28, and the movable plates 29. are sufficiently spaced therefrom so that plates 29 in the sition other.

Movable metal plates 29 are shown will have very little capaci y effect therewith, allowing a wider range of caacity variation. Two springs 32comprismg metal strips are connected at points 33 to end plates 28 and engage the side walls of the enclosing air-tight glass bulb or cas ing32 at points 34 to support the'"'con-' denser yieldingly against longitudinal movement which mighteinjure casing 32. This casing may be a bulb or tube as shown, preferably of glass or' other non-magnetic madescrl terial for a purpose tobe described additional to the property of glass in readily perthe sealing in of metal terminal leads.

The relative movable condenser plates or conductors o the drawing preferab y are constructed of materials such as nickel, etc., (as enumerated below) for the reasons below stated and treated as.described below,

inserted within the casin or bulb 32, sealeda conductor 38 extending through and sealedin casing 32 and connected to a spiral conducting coil 37 connected to one end of the metal shaft 30, but of flexible wire arranged with the slack of the coil as shown to allow the free rotation of shaft 30 carrying the movable conductors. The parts of terminals 36 and 38 which extend thru casing 32, and

'are fixedly sealed therein, preferably are of platinum when the casingis of glass. Thus these terminal leads are independent I of thieaapacity-varying means now to be The left'end of the shaft 30 terminates in a magnet 39 of suitable magnetic material such as iron, steel or nickel, supported in spaced relation to the end of the tube 32. This magnet has the poles 40 and 41. The encased condenser is supported in any suitable manner on a base 42. A horseshoe magnet '43,-located outside casing 32, journaledin the support 42 at 44 and provided with an actuating knob 45, embraces the end of the non-magnetic casing 32. (as glass, as described) adjacent to exterior magnet 39. As magnet 43 is rotated, this rotation will communicated to the variable condenser magnetically through the co-acting interior magnet, 39, thus providing means for vary-' ing the capacity of the condenser-without danger of impairing the high degree of vacuum necessary to this invention, or in any instance, without the necessity of extending a mechanically moving part thru casing 32. Either of the magnets39. 43 may be a soft iron or nickel armature, if so a desired. And the invention includes means alternative with magnet 43 and co-acting magnet 39 for causing, outside the enclosmg casing, a magnetic field which extends thru and inside the casing to cause the relatlve movement of the condenser conductors.

The invention also includes operable outside the casing but acting or effective in side the casing without afl'ecting the vacutheir axis 30 is horizontal as shown) to hang down under the influence of gravity in a position 180 from that shown (for clearnes's) in the drawing, therefore this condenser pomsses the ability to have its capacity varied by rotat' the casing 32 (and consequently the xed plates 25) around the longitudinal axis of the casing, the movable plates hanging down by gravity, remaining stationary. Thus the capacity of the condenser can be varied, with or without the operation of a magnetic field, by a rotation of the entire casing 32 in its supports shown as secured to base 42; and owing to the disclosed construction each 0 the relatively movableconductors can be moved with respect to the other.

The order of vacuum or exhaustion which cxists in a condenser containing a dielectric such as above described preferably is extremely high, such that no appreciable gas ionization takes place to cause losses while the condenser is in operation, which condition is obtained, for example, by a pressure of the order of a, millionth of a millimeter. Such exhaustion may be obtained by any well-known means such as a Gaede or molecular pump, or Langmuirs condensation pump.

All materials inside the casing, when a. vacuum dielectric is employed, are to be suitably treated to remove gases (occluded or otherwise) according to any of the wellknown processes in use for the production of high vacuum apparatus. Such treatment may consist, for example, in initially (before assembling in the casing) treating these materials to remove gases preliminarily as by heat or other treatments. In addition, it is advisable, after asembling in the easing, to subject the contained -mater1als to further treatment to remove any residual gases. This final-treatment may consist of a bombardment of the materials from a heated filament which is located within the casing temporarily or otherwise. I prefer to use as a first treatment the well know'nf method of removing gases from metals consisting of the use of the Northru high-frequency electrical furnace. In such case, my entire condenser, while undergoing its exhaustion, is placed within the 'fiel'd of a coil carrying high frequency current. This heats the metal parts inside the condensercasing. thereby driving ofi and removing gases before the-casing is completely exhausted and sealed of. The materials used in these vacuum condensers should be of such a nature that the gases my be easily shoul mechanically supporti removed by the above'descrilied processes. Therefore, in constructing the condensers, nickel tungsten, molybdenum or rolled steel d be used wherever possible in constructing all parts.

By the above construction and invention, a condenser in which theplates' 1 and 2 are separated a centimeter can be constructed to stand a million volts. In such a condenser and with the vacuum dielectric of the order specified, the loss is practically zero, being limited to the minute Joulean losses in the metal plates and leads, and the minute losses in the dielectric surrounding the terminals, and the minute losses in the supporting dielectric material.

While the condenser hereof preferably has a vacuum dielectric in general as above described as to preference in detail, the important aspect of the invention hereinafter claimed is the construction and arrangement involving the variation of the condenser capacity by relative movement of the conducting plates inside the casing and separated from one another by any suitable dielectric; and particularly, when the dielectric is a vacuum, or when the relatively movable conductors are wholly supported and enclosed within the casing, a means for causing such lelative movements which does not affect the vacuum seal or enclosure of the casing.

It is to be understood that the invention is not limited to the embodiments and featuies s ifically shown anddescribed herein, but t t such embodiments and features are subjcct to changes and modifications without any departure from the spirit of the invention.

I particularly point out and distinctly claim the improvement, or combination which I c aim as my invention or discovery, as follows 1. A variable electrical condenser comprising electrical conductors which are movable relative to oneanother to permit variation of the condenser capacity; a vacuum casing surroundinge said conductors and a vacuum dielectric tween them, said casing both said conductors m positions spaced 'om one another by the vacuum dielectric; and means causing variation of the condenser capacity by relative movement of said conductors in their vacuum-spaced relation to one another.

2. A variable electrical condenser comprising electrical conductors which are movable relative to one another to permit variation of the condenser capacity; a vacuinn casmg surrounding said conductors and a vacuum dielectric between them; means causing variation of the condenser capacity by movement of said conductors in their vacuum-spaced relation to one another; and condenser terminal leads which are independentof said varying means, electrically connected to the respective vacuum-spaced conductors, and which extend thru said vacuum casing to the exterior thereof and are fixedly sealed in the wall thereof.

3. A variable electrical condenser com- 4. An electrical condenser com risin relatively movable conducting plates ar-' ranged in spaced relation to each other and constituting positive and negative conducting plates of the condenser, a vacuum casing in which said relatively movable plates are yieldingly supported and from which the air has been exhausted forming a vacuum dielectric between said lates, terminals connected to said relative y movable plates and passing through said casing, a magnetic member within the casing and fixed to said movable plates, and a second magnetic mem-' ber suitably supported outside of said casing and arranged in proximity to the portion of the casing in which the first-mentioned magnetic member is located, whereby the movement of the second magnetic member will impart a corresponding movement to the magnetic member and movable plateswithin the casing to vary the capacity of the condenser. v 5. A variable electrical condenser coniprising electrical conductors which are movable relative to one another to permit variation of the condenser capacity; a vacuum casing surroimding said conductors and a vacuum dielectric between them,'said casing constituted of materialpermitting extension thru it of a magnetic field; and means including a generator of a magnetic field and located outside the casing but establishing a magnetic field within the casing which causes relative movement of said conductors and a consequent variation of the condenser capacity. 7

6. A variable electrical condenser comprising electrical conductors which are relatively rotatable to permit variation of the condenser capacity; a vacuum casing of insulating material enclosing said condenser conductors and a vacuum dielectric between them in the casing; both said condenser conductors being supported by said vacuum casing and located entirely within it, one being mounted rotatably relative to the insulating casing and the other being fixed relative to said casing; and condenser terminal leads extending from said conductors out thru the wall of the insulating vacuum casing and sealed in said wall.

7. A variable electrical vacuum condenser comprising relatively movable conductors permitting variation of the condenser caacity; a vacuum casing enclosin said consuctors and a vacuum dielectric 'between them; terminal leads extending thru and fixedly sealed in said casing and electrically connected withsaid conductors to permit their relative movement; and means independent of' said leads and located outside said casing for moving a magnetic field inside thecasin thereby causing relative movement of said condenser conductors.

8. A variable electrical condenser comprising electrical conductors'separated from one another by a dielectric and movable relative to one another to permit variation of the condenser capacity; a casing enclosing said conductors and dielectric and mechanically supporting both of said conductors;

means causmgvariation of the condenser capacity by causing relative movement of said conductors; and terminal leads independent of said varying means, electrically connected to said respective'conductors, and passing thru said enclosing casing to the exterior thereof. i

9. A variable electrical condenser comprising a main support, two relatively movable oonductors insulatedfrom one another and separated by a dielectric; a horizontal shaft which is rotatably, mounted on and relative to said main su port one of said conductors being mounted fixedl relative to said main support; and the ot er. of said conductors being fixedly mounted on said and the other conductor wholly enclosed by the casing being supported therein in mov-.

able relation thereto subject-to being "held by gravity in a fixed'position relative to the first conductor if the casing with s'aid first conductor be moved. I

A variable electrical-condenser coniprising condenser conductors one of which tively movable conductors respectively; y

and thru the wall of whic ass-mas ing to hold said movable clonductors1 in a iven ition' a cas' enc os' sai conuctor s fnd said hold i h g means; and means located. outside said casing for moving a magnetic field inside the casing and thereby correspondingly moving said movable conductor in opposition to the cited. of said holding means to vary the condenser capacity. i

12. A variable electrical condenser comprising electrical conductors which are movable relative to one another to permit variation of the condenser capacity; a casing enclosing said conductors and a dielectric betweenthem; means establishing a magnetic field acting inside the casing to control the relative movement-of said conductors; and means located outside the casing for movin said field to cause such relative movement 0 said conductors. 13. A variable electrical condenser comprising condenser conductors which are movable relative to one another to rmit variation of the condenser capacity; a vacuum casing of glass entirely enclos' said movable conductors and a vacuum dl-' electric between them; circuit leads extending from the exterior to the interior of the casing and fixedly sealed in the glass wall thereof, said leads being the only material things extending thru the casin wall;

means effective within the casing or controlling relative movement of said condenser-conductors therein; and a controlling device, located outside said vacuum casing, for causing operation of said moving means. 14. A variable electrical condenser comprising electrical conductors which are movable relative to one another to permit variation of the condenser capacity; a movable vacuum casing ofglass entirely surrounding said conductors and a vacuum dielectric between them; circuit leads extending from the exterior to the interior of the movable casing, fixedly sealed in the glass wall there-' of, and electrically connected to said relaone of said conductors'wholly'enclosed the casing being supported therein in fixed relation thereto subject to participation in movementvthereof; and the other conductor .wholly enclosed by said casing bein sup-f ported therein in movable relation t ereto subject by vity to remaining in fixed position relative to the first conductor, whereby is movable relative eachiof said conductors to the other.

15. A. variable electrical condenser com- I prising condenser conductois which arev mov-. able relative to one another to permit variation of. the condenser capacity; circuit leads is movable relative the other; means tend-- and in which wall they are sealed; whereby 18o v tive movement of said condenser conductors;

and means located outside said casing for moving said field to cause such relative v movement of said conductors.

16. A variable electrical condenser com- 10 prising a vacuum casing and conductors relatively movable therein and having a dielectric. between them consisting of the vacuous space enclosed by said casing; both said conductors being supported by said casing; and means operable outside said casing but acting inside the casing, without affecting the vacuum seal thereof, to cause relative movement of said interior conductors. JOHN A. PROCTOR. 

